[djknight]

Hello
I have been asked to fabricate a time capsule which would be underground for 50 years.
I am thinking that stainless steel would be the right material to use(316),but am a little unsure as to whether
an argon purge when fully sealing it would do in removing the oxygen. Or would silica gel type dessacant
suffice? The interior would be wrapped in ceramic wool type material before commencing of welding
Regards

[WerkSpace]

I would start the project with an old stainless beer keg.
In the past, I found liquid nitrogen bottles in the recycling yards. (about the same size)
When I cut it open with a table saw, I found lots of layers of thin paper and aluminum foil inside.

Hello, I have been asked to fabricate a time capsule which would be underground for 50 years.
I am thinking that stainless steel would be the right material to use(316),but am a little unsure as to whether
an argon purge when fully sealing it would do in removing the oxygen. Or would silica gel type dessacant
suffice? The interior would be wrapped in ceramic wool type material before commencing of welding
Regards

I like finding old stuff. Here's a photo of one of my dinosaur eggs. (found in the Alberta Badlands)

[djknight]

Thanks for the advice.Have you finished opening the egg yet!

[noddybrian]

Don't do it - remember how that went with dino DNA in Jurrasic Park ! - come to think of it Graboids come from eggs as well !

[Otto Nobedder]

I would start the project with an old stainless beer keg.
In the past, I found liquid nitrogen bottles in the recycling yards. (about the same size)
When I cut it open with a table saw, I found lots of layers of thin paper and aluminum foil inside.

That sounds like "superinsulation", actually alternating layers of tissue and Mylar. Common in vacuum-jacket vessels.

If I were to make a time capsule for 50 years, I'd use PVC pipe, seal/cap the ends with PVC cement, and make a provision to purge the vessel with dry nitrogen until completely dry, then replace the atmosphere with argon.

I recently saw the resurrection of a 30 YO time capsule done (almost) this way. Each item inside was individually vacuum-sealed, ala' "seal-a-meal", and every item came out unscathed. There was no provision to purge the capsule, so the primary protection was the seal-a-meal bags.

Steve S

[Superiorwelding]

I remember putting letters in a time capsule in grade school.
You could make a SS capsule very futuristic like and when they dig it up in 50 years they will be like "wow they were really advanced back then"
As far as actual advice, I would say that even if you purge with argon, unless you have a ppm meter, you will not know if all oxygen is out. If you do use SS, 316L would be a good choice, just make sure you weld it very good and do not allow any oxidation, so it won't rust.
If/when you make it, get pics up for us.
-Jonathan

[Braehill]

Pull a vacuum on it and forget about purging it with anything. If it's made well enough to hold a purge it should be tight enough to hold a vacuum and that means it will have the lowest amount of moisture.

Len

[weldin mike 27]

Lolz Graboids. My favourite movie. Id say each item vacuum sealed with some silica would be a good bet.

Mick

[WerkSpace]

My dinosaur eggs contain fossilized embryos as depicted in the following article.
http://www.museumoftheweird.com/news/20 ... sing-link/
The embryo is the small item next to the egg with the cracked shell. (This was found in a broken egg.)

[mcoe]

I will say this much, I found an old knife and dog tag with a metal detector on our property where an old house use to be. The knife blade is SS and the dog tag belonged to a WWII vet and at the time we found the tag and knife, the house that had stood there had been burnt and gone for about 60 years and there is not a bit of rust or corrosion on the blade. I had to dig about 3ft to get to it too. Just a little story I thought I would share.

[Antorcha]

You need to recommend a minimum of 50 THOUSAND years.Store them in a pure honey bath in a 317L vessel.
50 years from now, if there is life here, it will be too stupid to deal with that thing......already is-are-B !
https://www.youtube.com/watch?v=prLOjYqwaAc

[RichardH]

Pull a vacuum on it and forget about purging it with anything. If it's made well enough to hold a purge it should be tight enough to hold a vacuum and that means it will have the lowest amount of moisture.
Len

Reviving a stale thread, but why not take the opposite approach and pressurize it? You might have to contend with whatever moisture is in the container, but wouldn't it help to keep out moisture migration vs. a vacuum?

I like the seal-a-meal idea. Layers of protection. And when I think about pressurizing, I wonder why not use a gas cylinder, which is built to handle pressure and have done so over 50+ years in storage (albeit not buried)? I just wouldn't pressurize it too high (50psi?) for the sake of those opening it. Engrave instructions on the cylinder...

Cheers,
Richard

[djknight]

Hi,
Have not figured out what the atmospheric conditions will be inside the box.But now I have been told it is going to be 100 years the box is going to be 3mm(1/8) 316 sealed by welding, then covered in code 8(3.5mm) lead sheet lap welded all round.
I am wondering if the heat generated by the final sealing of the box when welding will create its own vacuum?
What is left inside an empty box if it is welded shut??

[RichardH]

Have not figured out what the atmospheric conditions will be inside the box.But now I have been told it is going to be 100 years the box is going to be 3mm(1/8) 316 sealed by welding, then covered in code 8(3.5mm) lead sheet lap welded all round.
I am wondering if the heat generated by the final sealing of the box when welding will create its own vacuum?
What is left inside an empty box if it is welded shut??

Hmmm. I'd expect you're right, that the heated air inside the box will create a vacuum as it cools. This would also suck on the molten weld joint if the air cooled faster than the steel, creating porosity on the inside of the weld, no?

It's generally a Really Bad Idea to weld on a sealed container because it's likely to explode from the gas expansion. This is kind of the reverse scenario, but it still strikes me as a bad idea. Not the least of which because you won't know for 100 years if the heat or the gases from the welding process kill the contents of the box. Or ditto for the process of cutting open the box.

Which is what led me to the idea of using a gas cylinder. Mechanical seal, yes, but they've been routinely shown to hold pressure for decades. If not repurposing one, why not duplicate their proven model (i.e., their method & materials for the seal), but in stainless?

[Paul_au]

I would just make it look fancy and pretty for the people that will put in the ground. Highly polished box type thing with a glass viewing panel with some kind of document viewable so they can all go oohhhh ahhhh before dumping it in the hole.

Put the actual contents within vacuum sealed bags and PVC pipe or something.

[djknight]

Have got a plan!
Fabricated highh density polyethylene box with items in seperate bags,argon purge,seal.
Stainless steel box inset lid purge, then welded except lid.
Lid off,wrap hdpe box in heatproof mat(not sourced yet).
Inset lid back in(not sure if purge now needed as the seam is upstanding from inside by approx 1")
Weld seam,purge,seal.
Code 8 lead lap welded all round.
Dig hole,bury.
Wait..........
Dig up on 200 year centenary of brownies(100 years time)
Open carefully!
I think that might be the plan,have not yet figured how to seal the purge,but one step at a time!

[weldin mike 27]

Note :

Must also figure out how to stay alive for the next hundred years, but baby steps eh?

Mick

[djknight]

If argon could be the answer to time CAPSULES maybe it is also the answer to time TRAVEL hohoho!

[Bill Beauregard]

While you haven't said how big it needs to be, or how you will seal it. I have an idea. Cut the top off a beer keg. make a bolted flange of 10 pieces each half of 1/2" by 2-1/2. With the two flanged surfaces bolted together through holes at the mitered corners, then TIG the flange to the two halfs of the keg. A stainless nipple can be welded in a hole fitted with a small check valve. Put the treasures in, bolt the flanges back together. Weld the seam, and around each bolt. Use the nipple with check valve, and a refrigeration vacuum pump to pull a hard vacuum for twenty four hours. The check valve will hold the vacuum while you weld up the end of the nipple.
A cheaper way would be to use a big welding tank, cut it near the top, put treasures in, stuff the tank with fiberglass insulation, weld the top back on. Use the threaded tapping to install nipple, check valve, and pull a hard vacuum. As heavy as these tanks are, 50 years is no problem. Our local small town water system had hand threaded galvanized schedule 40 pipe. It lasted 110 years before the threaded joints where the galvanized coating was cut away started to leak.

[Bill Beauregard]

My dinosaur eggs contain fossilized embryos as depicted in the following article.
http://www.museumoftheweird.com/news/20 ... sing-link/
The embryo is the small item next to the egg with the cracked shell. (This was found in a broken egg.)

That's astounding!

[djknight]

Finally got around to fabricating plastic box

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Second photo shows stainless top with hdpe gasket sandwiched inbetween two s.s layers

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Box is water tight to top,will test for full top seal up to about 1 bar.
To be continued....

[djknight]

Finished and buried, surrounded by concreteslabs!

Box with contents before purge

DSC_0082.JPG (28.53 KiB) Viewed 1264 times

Purged box in stainless

DSC_0085.JPG (30.54 KiB) Viewed 1264 times

Lead box ready for burial

DSC_0094.JPG (27.01 KiB) Viewed 1264 times

[xwrench]

Awesome job. I'll bet it'd do 300 years if it had to.

[weldin mike 27]

I'll put it in my diary. No doubt I'll still be moderating here in 50 years. PS....there's not a severed head in it is there? Al la Criminal Minds.

Mick

[Bill Beauregard]

I'll put it in my diary. No doubt I'll still be moderating here in 50 years. PS....there's not a severed head in it is there? Al la Criminal Minds.

Mick

Mick,

Don't be silly, We store them in the freezer until winter when we can put them in a backpack, and walk easily across the swamp. If you do it before a snow there will soon be no sign of it.